The present invention relates generally to a method and apparatus for detecting and measuring gaseous air pollutants such as those found in industrial exhaust streams from furnaces and the like. An increasing awareness of the hazards of air pollution in recent years has led to strict controls on a local and national level both in the United States and abroad over exhausting sulfur oxides, nitrogen oxides, and other inorganic and organic gases to the atmosphere. While great attention has been focused on economical means for removing these contaminants, somewhat less notice has been given to the concomitant problem of monitoring effluent gas streams to initially detect a pollution problem and, subsequently, to insure that emission abatement systems are operating properly. Conventional analytical techniques such as gas chromatography and colorimetric procedures have proven cumbersome and inadequate in accurately measuring gaseous contaminants present in concentrations on the order of a few parts per million or less; thus, new systems have been sought.